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Discussion Starter #1
i've been chasing a weird metallic tapping sound that occurs from 2800-3000rpm that sounded like rocker arms flapping or a lifter not pumping up. only happens while driving and while moving and only through that rpm range. i couldn't replicate it on the bike lift.

so far i totally went through primary, compensator, clutch. replaced lifters, readjusted pushrods, serviced and check rocker boxes and arms, pulled cam plate and checked cams, bearings, and lifters.

finally was able to put a borescope down the cylinders and found the rear piston looking like this. anyone have any ideas if this is normal??? the front cylinder had carbon but it wasn't broken apart and it looked like a normal piston that had been running.

think this has something to do with the noise i've been chasing?





 

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I think I'm chasing the same noise. Everyone tells me there is nothing wrong with my bike. It runs good so I cant argue, but the noise is concerning to me...I hope you find it.
 

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Discussion Starter #3
my whole deal with the noise is it's new at 36k on the clock. started on my last road trip. i'm not a fan of "new" noises of this nature

I think I'm chasing the same noise. Everyone tells me there is nothing wrong with my bike. It runs good so I cant argue, but the noise is concerning to me...I hope you find it.
 

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Piston looks normal. I bet the noise you are hearing is the rocker shaft against the bolt. Very common and you can get rid of it by installing a thing called Rocker Lockers.

It does look like you have some pretty good scratches on the cylinder wall though.
 

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That piston looks pretty god as far as build up. Shows some detonation, so the tune could use a little work still.

But that heat streak up the stud hole doesn't look good. Jugs been pertty hot.

IIWY, i'd run a leakage test and see what the rings are doing. Check it a a few locations in the bore.

After that I'd button it up and try to localize the noise a little better. If you can't duplicate it without a load on it, then crank-compensator-trans would be the areas of concern.
 

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Discussion Starter #6
roller rockers installed about 10k ago :smile:

Piston looks normal. I bet the noise you are hearing is the rocker shaft against the bolt. Very common and you can get rid of it by installing a thing called Rocker Lockers.

It does look like you have some pretty good scratches on the cylinder wall though.
 

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Discussion Starter #7
i did have an issue with the tune originally so think those marks are from a long time ago (i hope). my last tune was from bob at RC cycles and i have been running it for about 20k miles since he did the tune with no pinging.

i did a leakdown the other month and all was well. i didn't check different spots in the cylinder though as it is hard to turn the wheel once the air is pumped in. compression was good also.

compensator was replaced not too long ago and it is still pristine. no metal in transmission oil or metal when i took tranny cover off.

how would i check crank? anything else to check for transmission? can a bike lose a tune if an O2 sensor goes bad or anything like that? i am really starting to hit a wall. motor mounts? front stabilizer link?

That piston looks pretty god as far as build up. Shows some detonation, so the tune could use a little work still.

But that heat streak up the stud hole doesn't look good. Jugs been pertty hot.

IIWY, i'd run a leakage test and see what the rings are doing. Check it a a few locations in the bore.

After that I'd button it up and try to localize the noise a little better. If you can't duplicate it without a load on it, then crank-compensator-trans would be the areas of concern.
 

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You might want to vent the breather vents to the outside on the motor instead of them routed back into the throttle bodies. The oil going back through the motor is contributing to the carbon build up.
 
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You might want to vent the breather vents to the outside on the motor instead of them routed back into the throttle bodies. The oil going back through the motor is contributing to the carbon build up.
This is what I did a long time ago , and if the carbon just bugs you , remove the air cleaner , crank the bike up , let it get warm and take a squeeze bottle with water in it and shoot a couple good shots into the intake , do that at a high idle maybe 2000 max , it will hit the cylinder as steam and break up the carbon , but the carbon doesn't look bad , seen worser ..
 

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Discussion Starter #11
i didn't check the last time i had my cam chest out and am kicking myself for forgetting. i remember the oil pump and all races around the cam plate looked good.

my 3 ideas at this point are: something crank related, maybe transmission but doubtful as the oil was clean as the virgin mary and no metal upon inspection, maaayybe engine mounts.

i've put my foot on shifter, floorboards, kick stands while driving to see if that changed anything. grabbed the horn cover. checked belt tension. moved kickstand away from bike while driving.

it sounds like it is on top of engine like rocker cover area. i checked rocker arms, bolts, and everything else in rocker box area and no issues found. bolts did not have witness marks or scoring from the rocker arms.

this may be a dumb question...the front stabilizer engine mount...does that ever cause a rattle? mine has no back and forth play, but i've never oiled it or anything. i'm not even sure if it needs oiled or fails? all bolts verified tight.

Have you checked the crank run out ??
 

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roller rockers installed about 10k ago :smile:

That still may not do anything to stop the pivot shaft from rattling against the retaining bolt unless the builder addressed that specifically during assembly. i.e. Locking screw, or high heat locktite, or rocker lockers etc...


I could be wrong and it was just an area to consider looking. It would be easy to tell by pulling the rocker arms off and looking for shiny marks on the bolts that go down through the cut out area of the pivot shaft.


Let us know if you get it figured out.
 

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how would i check crank?
Well, IIWM, I would check the run out on both ends. Then with all those scratches I would pull the jugs and look for sparkles embedded in the piston skirts. Then check the big end rod play. But to be sure, I'd need more than some noise to make me pull it down. Twin cams are prolly the sloppiest fit motors anyone built in the last 20 years. With what

Or you can pull the access plug out of the sump cavity and replace it with a magnetic plug. See what collects on it. Be sure to heat that plug before you try to turn it out.

You get that thing on the dials and see .006 on the right, then its time to pull the primary and check the sprocket shaft. You'll prolly have .009 or more on the left.
 

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Discussion Starter #14
That still may not do anything to stop the pivot shaft from rattling against the retaining bolt unless the builder addressed that specifically during assembly. i.e. Locking screw, or high heat locktite, or rocker lockers etc...


I could be wrong and it was just an area to consider looking. It would be easy to tell by pulling the rocker arms off and looking for shiny marks on the bolts that go down through the cut out area of the pivot shaft.


Let us know if you get it figured out.
i was typing too fast yesterday. i installed rocker lockers, not roller rockers. bolts looked good when i had them out last.
 
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Well, IIWM, I would check the run out on both ends. Then with all those scratches I would pull the jugs and look for sparkles embedded in the piston skirts. Then check the big end rod play. But to be sure, I'd need more than some noise to make me pull it down. Twin cams are prolly the sloppiest fit motors anyone built in the last 20 years. With what

Or you can pull the access plug out of the sump cavity and replace it with a magnetic plug. See what collects on it. Be sure to heat that plug before you try to turn it out.

You get that thing on the dials and see .006 on the right, then its time to pull the primary and check the sprocket shaft. You'll prolly have .009 or more on the left.
i found my old notes from 2015 last time i checked runout. had .007 on the right side. and i am with you, not going to pull it down to that level for just a noise as annoying as it is.

on a side note, i see you are in south central PA. i grew up in carlisle if you know the town
 

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i didn't check the last time i had my cam chest out and am kicking myself for forgetting. i remember the oil pump and all races around the cam plate looked good.

my 3 ideas at this point are: something crank related, maybe transmission but doubtful as the oil was clean as the virgin mary and no metal upon inspection, maaayybe engine mounts.

i've put my foot on shifter, floorboards, kick stands while driving to see if that changed anything. grabbed the horn cover. checked belt tension. moved kickstand away from bike while driving.

it sounds like it is on top of engine like rocker cover area. i checked rocker arms, bolts, and everything else in rocker box area and no issues found. bolts did not have witness marks or scoring from the rocker arms.

this may be a dumb question...the front stabilizer engine mount...does that ever cause a rattle? mine has no back and forth play, but i've never oiled it or anything. i'm not even sure if it needs oiled or fails? all bolts verified tight.
Front stabilizer mount. There was a post recently about that on newer bike's. Needed some lube. Might want to find that thread and look it over.

Sent from my SM-G930V using Tapatalk
 

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i found my old notes from 2015 last time i checked runout. had .007 on the right side. and i am with you, not going to pull it down to that level for just a noise as annoying as it is.

on a side note, i see you are in south central PA. i grew up in carlisle if you know the town
If its 007 on the right you might want to have a look at the left some rainy weekend. (pretty much any week end of late) Just pull the cover and back the adjuster off a tooth or two and lock it the with a zip tie. Rotate the motor through by the comp and watch the chain. If its going snug to loose, you'll hear that under load. Basically the lefty bearing and the primary bearing are getting hammered on each rotation.

If its way out like .009, you might want to think about an adjustable tensioner. That way you can at least set it so it always has a little slack, even when the crank wobble is leaning to the front.

These auto tensioners keep the chain pretty tight, add to that the a .009 wobble is equal to more than an inch of chain slack when leaning towards the clutch, and you get a real tight chain when the wobble rotates to the front. Remember, that auto tensioner will take that slack out, then refuse to release the tension when it needs to.
 

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If its 007 on the right you might want to have a look at the left some rainy weekend. (pretty much any week end of late) Just pull the cover and back the adjuster off a tooth or two and lock it the with a zip tie. Rotate the motor through by the comp and watch the chain. If its going snug to loose, you'll hear that under load. Basically the lefty bearing and the primary bearing are getting hammered on each rotation.

If its way out like .009, you might want to think about an adjustable tensioner. That way you can at least set it so it always has a little slack, even when the crank wobble is leaning to the front.

These auto tensioners keep the chain pretty tight, add to that the a .009 wobble is equal to more than an inch of chain slack when leaning towards the clutch, and you get a real tight chain when the wobble rotates to the front. Remember, that auto tensioner will take that slack out, then refuse to release the tension when it needs to.
hmm interesting. that's a good idea for more testing. i'll have to give that a shot next time i am in there.
 
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